Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TILT CORRECTION SYSTEM AND METHOD FOR RAIL SEAT ABRASION
THIS IS CROSS REFERENCE TO RELATED APPLICATIONS
roooil This application is a continuation-in-part of U.S. Application S/N
12/465,473, entitled,
"SYSTEM AND METHOD FOR INSPECTING SURFACES USING OPTICAL
WAVELENGTH FILTERING, filed May 13, 2009, naming John Nagle, Steven C. Orrell,
Christopher Villar, and Charlie Aaron as inventors, which is a continuation-in-
part of US
Application S/N 11/172.,618, entitled, "SYSTEM AND METHOD FOR INSPECTING
RAILROAD TRACK, filed June 30, 2005 and naming John Nagle, Christopher Villar
and
Steven Orrell as inventors, which is a non-provisional application claiming
benefit of U.S.
Provisional Application S/N 60/584,769, also entitled, "SYSTEM AND METHOD FOR
INSPECTING RAILROAD TRACK, filed June 30, 2004, naming John Nagle and Steven
C.
Orrell as inventors, each being hereby incorporated by reference in their
entirety.
FIELD OF THE INVENTION
100021 The present invention relates generally to systems and methods for
inspecting railroad
surfaces and, more particularly to systems and methods for determining rail
seat abrasion via the
utilization of tilt correction algorithms.
BACKGROUND OF THE INVENTION
10003] Railroads are generally constructed on a base layer of compacted,
crushed stone material.
A layer of gravel ballast rests on top of this stone layer. Crossties are laid
in and on this ballast
layer, and two parallel steel rails are attached to the crossties with
fasteners. The majority of
crossties in service are made of wood. Various other materials are used such
as concrete, steel,
and composite or recycled material in the manufacture of crossties.
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10004] The ties are normally paced on top of the track ballast. The remaining
construction
differs slightly depending on the type of tie material useds. If wood ties are
used, tie plates are
then placed on top of the ties. Rails are then placed on top of the tie
plates. The rails are then
fastened. to the ties through the use of spikes or bilts driven through holes
in the tie plates. When
concrete ties are used, rails are placed on top of the ties, with a thin
polymer pad preventing
direct contact between the steel and the concrete. Steel clips are often used
to fasten the rail to
the tie. Additional track ballast is then used to fill spaces between and
around the ties to assist in
anchoring.
]0005] Normal railroad traffic causes friction between ties and rails, as well
as rails and spikes,
bolts, screws, or clips, and the surface under the ties. Of particular concern
is friction at the point
where the rail seats against the tie. Wear at this point, also known as rail
seat abrasion, directly
impacts the life of the tie by causing it to loosen from the rail. In spite of
the pads used between
rails and concrete ties,, rail seat abrasion remains a continuing problem with
concrete ties.
]0006] When the rail seat wears, it affects the amount of tension on the
fastener so that the rail
mounting force required to firmly affix it to the tie is not achieved. Should
this happen, the rail
can slide against the tie, which increases the rate of abrasion. Rail slide
can also cause rail welds
to pull apart, either from stress or from temperature misalignments. Another
concern with rail
seat abrasion is that it increases the exposure of the surface of the ties to
environmental
conditions, further accelerating rail seat abrasion and tie degradation.
Additional causes or
contributing factors to rail seat abrasion can include manufacturing defects,
temperature variation
patterns, railroad arrangements, such as curvature, grade, and banking, and
the state of the pad
used between rail and tie.
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[0007] Measurement has been conducted to monitor the wear of concrete ties,
either by direct
manual measurement, or through the use of electronic devices installed below
individual railroad
ties. All previous methods have proved either unreliable, hazardous, labor-
intensive, requiring
extensive equipment installation, or having a major impact on the availability
of railroads to train
traffic.
[.0008) In view of the foregoing, the present invention is directed to
overcoming, or at least
reducing the effects of, one or more of the problems set forth above, thereby
providing a system
capable of predicting instances of rail track abrasion without the need for
hazardous and
unreliable manual measurements or costly electronic measurement devices.
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SUMMARY OF THE DISCLOSURE
[00091 Exemplary systems and methods for determining rail seat abrasion of a
rail road track are
disclosed. Embodiments of the disclosed system includes an inspection system
comprising
lasers, cameras, and processors adapted to determine whether rail seat
abrasion is present along
the track. The processor employs a mathematics based algorithm which
compensates for tilt
encountered as the inspection system moves along the track.
[0010] Exemplary methods of the present invention comprise the steps of moving
the inspection
system along the track, receiving image data corresponding to the track,
determining
measurements of the rail seat abrasion for various portions of the track,
wherein the
measurements adjust for tilt encountered as the inspection system moves along
the track.
[ooni By mounting measurement devices on the inspection vehicle that traverses
the track,
taking precise measurements of the height of the rail and the tie, and
adjusting these
measurements for any expected tilt encountered, instances of rail track
abrasion can be predicted
without the need for hazardous raising of rails for unreliable and time-
consuming manual
measurements, or for costly and labor intensive installation of electronic
measurement devices
under individual ties.
[00121 The foregoing summary is not intended to summarize each potential
embodiment or
every aspect of the subject matter of the present disclosure.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The foregoing summary, preferred embodiments, and other aspects of the
subject matter
of the present disclosure will be best understood with reference to a detailed
description of
specific embodiments, which follows, when read in conjunction with the
accompanying
drawings, in which:
[0014] Figure 1 schematically illustrates an embodiment of the disclosed
inspection system.
[oois] Figure 2 illustrates a portion of an embodiment of a system for
inspecting railroad track
according to certain teachings of the present disclosure.
[0016] Figure 3 illustrates an example frame of a portion of railroad track
obtained with the
disclosed inspection system.
[00171 Figures 4A-4C illustrate example frames of railroad track obtained with
the disclosed
inspection system for determining the spacing between the crossties.
[0018] Figure 5 illustrates an example frame of railroad track obtained with
the disclosed
inspection system for determining the angle of the crosstie with respect to
the rail.
[0019] Figures 6A-6C illustrate example frames of railroad track obtained with
the disclosed
inspection system for determining a break or separation in the rail.
[0020] Figures 7A-7B illustrate example frames of railroad track obtained with
the disclosed
inspection system for determining wear of the rail.
[0021] Figure 8 illustrates an example frame of railroad track obtained with
the disclosed
inspection system for determining defects in the crosstie, spacing of the
rail, size of the crossties,
and ballast height relative to the crosstie.
[00221 Figure 9 illustrates an example frame of railroad track obtained with
the disclosed
inspection system for determining a raised spike.
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[0023] Figure 10 illustrates an example frame of railroad track obtained with
the disclosed
inspection system for determining a missing tie plate.
[0024] Figures 11 and 12 illustrate three-dimensional compilations of image
data obtained with
the disclosed inspection system.
1002s] Figures 13 and 14 illustrate an alternate exemplary embodiment of the
present invention.
[0026] Figure 15 illustrates an exemplary embodiment of a camera according to
the present
invention.
10027] Figure 16 illustrates a graph plotting the energy of the sun's solar
radiation at specific
wavelengths according to an exemplary embodiment of the present invention.
[oo28] Figure 17 illustrates a profile image of a rail road track tilted
according to an exemplary
embodiment of the present invention.
[0029] Figure 18 is a flow chart illustrating a method of determining rail
seat abrasion according
to an exemplary embodiment of the present invention.
[0030] While the disclosed inspection system and associated methods are
susceptible to various
modifications and alternative forms, specific embodiments thereof have been
shown by way of
example in the drawings and are herein described in detail. The figures and
written description
are not intended to limit the scope of the disclosed inventive concepts in any
manner. Rather, the
figures and written description are provided to illustrate the disclosed
inventive concepts to a
person skilled in the art by reference to particular embodiments, as required
by 35 U.S.C. 112.
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DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
Io03i1 Referring to Figures 1 and 2, an exemplary embodiment of a system 30
for inspecting
railroad track according to certain teachings of the present disclosure is
illustrated. In Figure 1,
the disclosed inspection system 30 is schematically illustrated relative to a
railroad track. In
Figure 2, a portion of the disclosed inspection system 30 is illustrated in a
perspective view
relative to railroad track.
100321 As best shown in Figure 1, the exemplary disclosed inspection system 30
includes a light
generator such as a laser 40, a device for receiving light reflected from the
area to be inspected
such as a camera 50, and a processing device 60. In the implementation shown
in Figure 1, the
disclosed inspection system 30 is used to survey the track bed of a railroad
track. Although the
disclosed inspection system and associated methods are described for use in
inspecting railroad
track, it will be appreciated with the benefit of the present disclosure that
the disclosed system
and method can be used in other areas and in industries where surfaces or
components require
inspection. For example, the. disclosed inspection system and method can be
used to inspect
roads, electrical lines, piping, or other networks or systems.
[00331 The track bed includes crossties 10, rails 12, tie plates 14, spikes
16, and ballast 18.
Briefly, the laser 40 projects a beam 42 of laser light at the track bed. The
beam 42 produces a
projected line L, shown in Figure 2, on the track bed that follows the
contours of the surfaces and
components of the track bed. The light receiver, camera 50, captures an image
of the line L of
laser light 42 projected on the track bed. The camera 50 sends the captured
image to the
processing device 60 for processing and analysis as described in more detail
below.
100341 As best shown in exemplary embodiment of Figure 2, pairs of lasers 40
and cameras 50
are positioned above each one of the rails 12 of the track. The lasers 40 and
the cameras 50 can
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be assembled onto a rigid framework 32, which can be mounted on an inspection
vehicle (not
shown) or other device moving along the track so as to maintain the inspection
system 30 in the
proper position. Only a portion of the framework 32 is shown in Figure 2 for
simplicity.
However, it is understood that other known components for the framework 32 may
be needed to
mount the lasers 40 and the cameras 50 on an inspection vehicle.
[003s1 In general, the inspection vehicle can be any suitable vehicle for
traveling along the
railroad track. For example, a common practice in the art is to equip a normal
highway vehicle,
such as a pick-up truck, with "hi-rail" gear mounted to the frame of the
vehicle. Hi-rail gear
typically includes a set of undersized railroad stock wheels that allow the
highway vehicle to ride
along the rails. In one embodiment, then, the framework 32 of the disclosed
inspection system
30 can be mounted in the bed of a pick-up truck having "hi-rail" gear.
Alternatively, the
inspection vehicle can be maintenance of way (MoW) equipment that is
specifically designed for
working along the railroad track. In addition, the disclosed inspection system
30 can be mounted
on a chassis that is towed by a vehicle or can be mounted on a locomotive or
freight car.
100361 As best shown in Figure 2, the lasers 40 project a beam 42 of light
having a
predetermined angular spread P. The angular spreads (3 of the two lasers 40
cover substantially
the entire surface of the track bed. In this way, the lasers 40 produce a
projected line L that is
substantially straight and extends substantially across the track bed. Each
laser 40 preferably
produces a beam 42 having an angular spread 1i of about 60-degrees and covers
approximately
one half of the track bed, Preferably, the lasers 40 project the beam 42
substantially
perpendicular to the surface of the track. Alternatively, a single laser could
be used that is
positioned such as to create the projected line L across the track bed.
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[00371 In addition, the lasers 40 are preferably infrared lasers having 4-
watts of optical output
and producing light at an infrared wavelength of about 810-nm. The relatively
high optical
output of the lasers 40 helps reduce effects of ambient light so that
shielding is not necessary. A
suitable laser for the disclosed inspection system 30 includes a Magnum laser
manufactured by
Stocker Yale. The parameters described above for the lasers 40 are preferred
for inspecting the
surface of a railroad track. However, those ordinarily skilled in the art
having the benefit of this
disclosure realize the present invention may be utilized to inspect a variety
of other surfaces.
Other implementations of the disclosed inspection system 30 can use an
alternate number of light
sources as well as different wavelengths, optical outputs, and angular
spreads.
[0038] As best shown in Figure 2, the cameras 50 are positioned adjacent the
lasers 40. As best
shown in Figure 1, the cameras. 50 are mounted at an angle 0 with respect to
the beam 42 of light
projected from the lasers 40. In one embodiment, the cameras are positioned at
an angle 0 of
about 60-degrees. As the disclosed inspection system 30 is moved along the
track, the cameras
50 capture an image or frame of the track bed at small, regular increments.
Preferably, the
cameras 50 are capable of a substantially high frame rate, such as about 5405
frames per second.
[0039 Each still image or frame captured by the cameras 50 is then filtered
and processed to
isolate the contoured laser line L projected on the track bed. The cameras 50
are fitted with
band-pass filters 52 that allow only the radiant energy substantially at. the
preferred infrared
wavelength of the lasers 40 to pass. Because the wavelength of the lasers 40
is about 810-nm,
the band-pass filters 52 of the cameras 50 can eliminate substantially all
ambient light so that the
camera 50 acquires a substantially clear, still image of the projected line L
of light from the
lasers 40.
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[004x] Each of the two cameras 50 send image data directly to the processing
device or
computer 60 via wired or wireless transmission lines. Preferably, the camera
50 includes a
processor 54 capable of converting or formatting the captured image of the
projected line L into
a dimensional profile that is sent directly to the processing device or
computer 60. The ability of
the camera 50 to process or format the captured image in this way can
eliminate the need for
expensive post processors or high-speed frame grabbers. A suitable camera for
the disclosed
inspection system 30 having such processing abilities includes a Ranger M50
manufactured by
IVP Integrated Vision Products, Inc.
(00411 Among other common components, the processing device or computer 60
includes a
microprocessor, inputs, outputs, and a data storage device 62. The data
storage device 62 can
include a hard drive, a non-volatile storage medium, a flash memory, tape, or
CD-ROM. The
processing device 60 can further include an input/display 68 for a track
inspector to input and
review data and to operate the disclosed inspection system 30. The processing
device 60
operates with suitable software programs for storing and analyzing the various
data obtained
with the disclosed inspection system 30. For example, the processing device 60
can have any
suitable image processing software, such as Matrox MIL, Common VisionBlox,
Labview,
eVision, Halcon, and IVP Ranger. For example, the processing device 60 can
have image
processing tools known in the art for analyzing image data from the cameras 50
such as Region
of Interest (ROI) tools, filtering tools, blob tools, edge finders, histogram
tools, and others.
[0042 To effectively process all of the data obtained with the disclosed
inspection system 30,
the processing device 60 in a preferred embodiment includes a computer having
a fast processor,
such as an Intel Pentium 4 processor capable of running at 2.8 GHz. To
effectively store all of
the data obtained with the disclosed inspection system 30, the storage device.
62 preferably
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includes two large-capacity hard drives configured to use both read/write
mechanisms
simultaneously as one drive, which is also known as a .Redundant Array of
Independent Disks
(RAID) system. The fast processor of the processing device 60 and the dual
hard drives of the
storage device 62 allow for sustained real-time storage of the data obtained
with the disclosed
inspection system 30. In a preferred embodiment, the power for the disclosed
inspection system
30 can be provided by 110 V AC power from a belt driven generator running
directly off the
engine of the inspection vehicle.
[0043] With the beams 42 projected onto the irregular surface of the track and
viewed at an
angle, the projected line L shown in Figure 2 follows the contours of the
surface and components
of the track bed. An example image or.frame showing the projected line L of
the track bed is
shown in Figure 3. The image data or frame includes a plurality of pixels
given X-Y coordinates
and shows a contour of the track bed captured by the cameras 50. Due to
filtering and other
image processing techniques known in the art,. the image includes two pixel
values, where the
dark pixels represent the contour of the track bed. Every pixel of a given
image data is given the
same Z-coordinate, which represents the particular position along the length
of the track at which
the image data was captured. In this manner, a plurality of captured images
produce a three-
dimensional scan of the track bed in which each image of the scan has X-Y
coordinates showing
the contour of the track bed and has a Z-coordinate representing the
particular position of the
contour along the length of rail.
10044 It is understood that the speed at which an image is captured is limited
by the width and
height of the scanned area, the distance between the discrete still images,
the resolution of the
still images, the maximum frame rate of the cameras 50, the processing speed
of the computer
60, and the write speed of the data storage device 62. For a railroad
application of the disclosed
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inspection system 30, one preferred example is spacing between still images or
frames captured
by the cameras 50 of about 0.1-inch, a preferred velocity of the inspection
vehicle of about 30-
mph, a preferred height of the scanned area of approximately 10 inches, and a
preferred width of
the scanned area of about 10-feet across the width of the track bed. To
satisfy these preferred
parameters, a camera system capable of about 5405 frames per second and a
computer system
capable of processing and recording at about 8.3 MPS is preferred. Each frame
or image, such as
shown in Figure 3, may require about 1,536 bytes of storage. With a frame
captured at about
every 0.1-inches along the length of track, about 633,600 frames would be
captured for one mile
of track and would require 0.973 gigabytes of storage space.
1004sj Another embodiment and as shown in Figure 1,. the disclosed inspection
system 30 may
further include a Global Position System (GPS) receiver 64 for obtaining
geographical locations
of the inspection vehicle when inspecting the railroad track. The GPS receiver
64 can include
any suitable GPS receiver known in the art for obtaining geographical
locations. For example,
the GPS receiver 64 can be an independent, commercially available unit mounted
on the
inspection vehicle and connected to the processing device 60 with a suitable
cable connection
and input/output interface. The GPS receiver 64 can obtain the geographical
location using a
differential or non-differential GPS system. Techniques for obtaining
substantially accurate
location and time data with a GPS receiver 64 are well known in the art and
are not discussed
further. The geographical locations are sent to the processing device 60 and
can be compiled
with the image data of the track bed.
(0046] When the image data from the cameras 50 is recorded, the geographical
location of the
frame can also be recorded. Eliminating a continuous stream of geographical
location data from
the GPS receiver 64 to the computer 60. can free the processor time available
for capturing the
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image data with the processing device 60. Therefore, the GPS receiver 64
preferably feeds data
to an auxiliary module 65. The auxiliary module 65 packages this data and
sends the data to the
processing device or computer 60 when queried. In addition to obtaining
geographical location
data, the GPS receiver 64 can obtain time data. Furthermore, the location and
time data obtained
with the GPS receiver 64 can be used to determine other variables, such as the
speed of the
inspection vehicle, which can be used for various purposes disclosed herein.
Thus, the disclosed
inspection system 30 can use data from the GPS receiver 64 to trigger the
cameras 50 to capture
a still image of the track bed at about every 0.1-inches along the rail.
100471 In an alternative exemplary embodiment and as shown in Figure 1, the
disclosed
inspection system 30 can include a distance device 66 for obtaining
geographical locations of the
inspection vehicle when inspecting the rail. The distance device 66 can be an
encoder that
counts wheel revolutions or partial revolutions as the inspection vehicle
moves along the rail or
can be the existing odometer sensor on the inspection vehicle. The distance
device 66 can
provide location data to the processing device 60. Using the distance device
66, the disclosed
inspection system 30 can trigger the cameras 50 to capture a still image of
the track bed at about
every 0.1-inches along the rail.
[0048] In another exemplary embodiment, the disclosed inspection system 30 can
capture still
images of the track bed at or near the maximum frame rate of the cameras 50
without being
triggered by the GPS receiver 64 or distance device 66. For example, the
cameras 50 and
processing device 60 can operate at or near the maximum frame rate while the
inspection vehicle
travels along the track. Using the known average width of a crosstie 10 or tie
plate 14, the
disclosed inspection system 30 can calculate the velocity of the inspection
vehicle. The
disclosed system can then delete any extra frames to reduce data storage so
that the retained
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frames would have an approximate spacing of 0.1-inch. It is understood that
exact spacing of
0.1-inch may not always be possible, but the spacing will be known and may be
between 0.05"
and 0.1". In this embodiment, the same number of frames must be discarded
between each
retained frame on a given tie so that frame spacing remains uniform. For
example, if the tie
plates are known to be 8-inches wide and 244 frames are captured for a
specific tie plate, then
two frames can be discarded between each retained frame. If the entire set of
frames were
numbered 1 through 244, then the retained frames would be those numbered: 1,
4, 7, 10,... 241,
244. The retained 82 frames would have a calculated spacing of 0.098-inch.
[00491 Alternatively, the disclosed system could interpolate between any two
captured frames to
create a new third frame at any desired location along the track. Some frames
could then be
discarded to achieve the exact frame spacing desired.
[0050] After the disclosed inspection system 30 completes a survey of railroad
track, computer
analysis of the image data is performed. The computer analysis can be
performed by the
processing device or computer 60 located in the inspection vehicle.
Alternatively, the computer
analysis can be performed by another computer system having image processing
software known
in the art. The computer analysis searches the image data and determines or
detects locations
along the track where defects occur or where allowable tolerances of the
railroad track are not
maintained. For a particular implementation, the computer analysis can be
customized or
changed. The geographic locations of defects or unallowable tolerances can be
provided. so that
appropriate repairs can be made or maintenance work can be scheduled.
[nosxr A number of measurable aspects of the railroad track can be determined
or detected from
the image data of the track bed obtained with the disclosed inspection system
and associated
methods. In examples that follow, a number of such measurable aspects are
discussed, and
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various techniques for analyzing the measurable aspects are disclosed. It will
be appreciated that
these and other measurable aspects of the railroad track can be determined or
detected from the
image data of the track bed obtained with the disclosed inspection system. In
addition, it will be
appreciated that other techniques known in the art for analyzing the image
data can be used with
the disclosed inspection system and associated methods, and that surfaces
other than railroad
components may be inspected. Accordingly, the disclosed inspection system and
associated
methods are not intended to be limited to railroad inspection or the
measurable aspects and
particular techniques described herein.
[0052[ For clarity, Figures 11 and 12 illustrate example compilations of image
data obtained
with the disclosed inspection system and associated methods. Figure 11 has a
plurality of
compiled image data showing a portion of a crosstie, tie plate, and rail in a
perspective view.
Figure 12 has a. plurality of compiled image data showing a more detailed
perspective view. As
can be seen in Figures I 1-12, the compiled image data forms a three-
dimensional representation
(X, Y, and Z) of the area of the track bed. The representation has substantial
detail, and various
aspects of the components of the track bed can be measured. In Figures 11-12,
for example,
cracks or splits in the crosstie 10 are visible. Also, the height of the
crosstie 10 with respect to
the ballast layer 18 is visible. The orientation and heights of the tie plate
14 and rail 12 are
visible. These and other details can be obtained with the disclosed inspection
system and
associated methods as described in more detail below.
[0053[ In one example, the spacing between crossties can be determined from
the plurality of
image data. Referring to Figures 4A-4C, example frames of the track bed
obtained with. the
disclosed inspection system 30 are illustrated that can be used to determine
the spacing between
the crossties 10. Figure 4A shows an end frame F1 having a contour of a first
crosstie 10 that is
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at position Z1 along the track. This end frame F1 may designate the last frame
showing this
crosstie 10. Figure 4B shows an intermediate frame F2 captured some time after
the end frame
F1 and at a further position Z2 along the track. This intermediate frame F2
lacks a crosstie
because it designates a location between crossties of the track. It is
understood that a plurality of
such intermediate frames will follow the end frame F1 of Figure 4A. Figure 4C
shows an end
frame F3 having another crosstie 10' that is at further position Z3 along the
track. Computer
analysis can determine the spacing between crossties 10 and 10' by, for
example, first counting
the number of such intermediate frames F2 lacking a crosstie. This number of
intermediate
frames F2 can then be multiplied by the known spacing between frames (e.g.,
0.1-inch) to
calculate the distance between crossties 10 and 10'. In this way, a
substantially accurate
measurement between crossties of the track bed can be obtained without the
need for a track
inspector to physically inspect the crossties. Instead, the image data that
forms the three-
dimensional scan of the track bed is used.
100541 Determining whether a frame has a crosstie or not can be performed by
imaging
techniques known in the art. For example and as shown in Figure 4A-4C, the
contour of a
crosstie 10 is expected in a region of interest R of the frames F1-F3.
Computer analysis can
search the region of interest R of a frame for pixels indicating the presence
of a crosstie. This
can be done, for example, by averaging or summing the value of pixels in the
region of interest
R. Because the contour of the crosstie is composed of dark pixels, the region
of interest R in a
frame Fl having a crosstie 10 will have a greater average or sum than the
region R in an
intermediate frame F2 lacking a crosstie.
[00551 In another example, the angles of the crossties with respect to the
rail can be determined
from the image data. Referring to Figure 5, an example frame of railroad track
obtained with the
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disclosed inspection system is illustrated. The angular orientation of the
heads of the rails 12 can
be represented by a line L1. The line L1 can be estimated, for example, by
best fit or curve
fitting techniques known in the art. Similarly, the angular orientation of the
crosstie 10 can be
represented by a line L2. The line L2 can also be estimated, for example, by
best fit or curve
fitting techniques known in the art. These lines L1 and L2 can be averaged
from several of the
frames along the Z-axis. near the crosstie 10. Computer analysis can then
determine the angular
relation between these lines LI-L2 to determine the angles of the ties with
respect to rail. This
condition would indicate either worn rail or a plate cut condition on a wooden
crosstie.
[0056[ In another example, a break in the rail can be determined from the
image data. Referring
to Figures 6A-6C, example frames Fl-F3 of railroad track obtained with the
disclosed inspection
system are illustrated that can be used to determine the separation of rail
12. Figure 6A shows an
end frame F1 having an end of a first rail 12 that is at position Z1 along the
track. This end
frame Fl designates the last frame showing this rail 12. Figure 6B shows an
intermediate frame
F2 captured some time after the end frame Fi and at a further position Z2
along the track. This
intermediate frame F2 lacks a rail because it represents a location between
rails of the track. It is
understood that a plurality of such intermediate frames F2 may follow the end
frame F1 of
Figure 6A. Figure 6C shows another end frame F3 having another rail 12' that
is at further
position Z3 along the track. Computer analysis can determine the spacing
between the rails 12
and 12', for example, by first counting the number of intermediate frames F2
lacking a rail. This
number of intermediate frames F2 can then be multiplied by the known spacing
between frames
(e.g., 0.1-inch) to. calculate the distance between the rails 12 and 12'.
[00571 Determining whether a frame has a rail 12 or not can be performed by
imaging
techniques known in the art. For example and as shown in Figure 6A-6C, the
contour of a rail 12
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is expected in a region of interest R of the frames F1-F3. Computer analysis
can search the
region of interest R of a frame for pixels indicating the presence of a rail
contour. This can be
done by averaging or summing the value of pixels in the region of interest,
for example.
Because the. contour of the rail is composed of dark pixels, the region of
interest R in a frame F1
having a rail 12 will have a greater average or sum than the region R in a
frame F2 lacking a
crosstie.
ioa581 In another example, the wear of the rails can be determined from the
image data.
Referring to Figures 7A-7B, example frames F1-F2, of railroad track obtained
with the disclosed
inspection system, are illustrated and can be used to determine wear of the
rail 12. Computer
analysis can determine if a rail 12 has wear, for example,. by determining
whether the distance
between the contour of the rail 12 and a reference point in a frame is less
than the same distance
in a prior frame. Figure 7A shows a frame Fl having rail 12 that is at a
position Z1 along the
track. The contour of the rail 12 lies within a region of interest R and at a
level L along the Y-
axis of the frame Fl. The contour of rail 12 is above a reference level L2,
which may be the
height of a tie plate, a measurable distance LD. As would be apparent to one
of ordinary skill in
the art having benefit of this disclosure, reference L2 may be located at a
number of reference
points such as tie plates 14,. spikes 16, or crossties. 10, for example.
Figure 7B shows another
frame F2 at another position Z2 along the track. At position Z2, the distance
LD is less between
the contour of the rail 12 and level L2 than at position Z1. Thus, frame F2
may indicate wear of
the rail 12 at the position Z2 along the track. As would be apparent to one of
ordinary skill in the
art having benefit of this disclosure, rail wear could also be determined
comparing frames taken
at different times, but at the same position along a track bed.
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[00591 In another example, the defects in the crossties 10 can be determined
from the image
data. As shown in Figure 8, an example frame of railroad. track obtained with
the disclosed
inspection system is shown. Defects D and D' are shown in the crosstie 10.
Computer analysis
can detect if the crosstie 10 has a defect, for example, by determining
whether portions D of the
contour of the cross tie lie outside a region of interest R or whether
portions D' of the. contour are
absent within the region R. As is known, defects in a crosstie can include
cracks, splits, or
breaks in the ties. Using the plurality of image data near such a defect,
computer analysis can
determine the width and length of the defect. For example and as seen in
Figures 11-12, the
plurality of image data can be used to estimate the width W and length L of
the crack shown in
the edge of the crosstie. In some instances, the computer analysis can
determine the depth of the
defect, for example, when the orientation of the defect allows light from the
laser to be projected
within the defect and to be captured by the camera. In one embodiment, the
angle between the
laser and the camera can be relatively small so that the light projecting into
a recessed defect can
still be captured by the camera positioned almost parallel to the beam of
laser light.
[00601 In another example, the spacing or gage of the rail or length of the
crossties can be
determined from the image data. In Figure 8, an edge detecting technique known
in the art can
be used to find edges of the rail contours 12 in the frame, and the distance
WI between the edges
can. be calculated to estimate the spacing of the rails 12. Similarly, an edge
detecting technique
known in the art can be used to find edges of the crosstie contour 10 in the
frame, and the
distance W l between the edges can be calculated to estimate the width. W2 of
the crosstie 10.
l006i1 In another example, the height of ballast 18 relative to the crosstie
10 can be determined
from the image data. In Figure 8, a line fitting technique can determine the
level of the ballast 18
and the level of the crosstie 10, and the difference between these levels can
estimate the height
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HB of the ballast 18 relative to the crosstie 10. In another example, the
scans of the railroad track
can be used to determine the size of stones in the ballast 18. This can be
done by analyzing a
region of interest having ballast 18 and estimating sizes of the ballast stone
using curvatures in
the contour of the ballast 18.
100621 In another example, raised spikes can. be detected from the image data.
Referring to
Figure 9, an example frame of railroad track obtained with the disclosed
inspection system is
illustrated. To determine whether there is a raised spike, a region of
interest R can be analyzed
to determine whether a portion of the contour representing a raised spike 16
occur within the
region R.
[00631 In other examples, missing tie plates, misaligned tie plates, or sunken
tie plates can be
detected from the image data. Referring. to Figure 10, an example frame of
railroad track
obtained with the disclosed inspection system is illustrated. The missing or
sunken tie plate can
be detected, for example, by analyzing a region of interest R and determining
whether a portion
of the contour representing a tie plate occurs or does not occur within the
region R. A
misaligned tie plate can be determined by line fitting the portion of the
contour of the tie plate
and comparing the orientation of the line to that of the crosstie, for
example.
100641 In regards to Figure 13, an alternative exemplary embodiment of
inspection system 30
will now be described. In this embodiment, inspection system 30 may be
constructed and
operated in the same way as described in relation to the previous embodiments.
However, in this
embodiment, the present. invention has been adapted to allow more efficient
daylight operation.
Inspection system 30 utilizes three line-generating lasers 40 mounted above
the surface to be
inspected. Center laser 40 is mounted in the center of framework 32 and scans
the surface area
within its angular spread i, while the outer two lasers 40 scan the outer
periphery of the
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inspected surface within their angular spread P. If, for example, a railroad
track were being.
inspected, center laser 40 could scan the full 9-foot tie, while the outer
lasers would scan the
rails.
100651 In this exemplary embodiment, the two outer lasers 40 are each tilted
outwardly away
from the center laser at an approximate angle y of 10 degrees. The two outer
lasers 40 are tilted
in. this embodiment in order to allow the inspection system 30 to be stowed
into a track bed, for
example, while still being capable of scanning a 9 foot tie of a railroad
track bed. By tilting
lasers 40 outward, the present invention achieves the scanning width required
to inspect the ties,
while still physically fitting within the trucks limit. However, since the
present invention can
also be used to inspect other surfaces, the two outer lasers 40 may not be
tilted whatsoever
dependent upon the practical requirements of that application.
[0066] Further referring, to the exemplary embodiment of Figure 13, lasers 40
are 7-watts lasers,
each having a 45 degree angular spread P. However, angular spread 0 could be
more or less
depending upon the distance between lasers 40 and the inspected surface as
understood by those
skilled in the art having the benefit of this disclosure. The intensity of the
laser line L (i.e., laser
beam L) projected by lasers 40 onto the inspected surface is at least 0.15
watts per inch of the
width of laser line L projected onto the surface. In the most preferred
embodiment, the intensity
is 0.18 watts per inch of the width of laser line L projected onto the
surface. The number of
lasers 40 utilized may be more or less than three, as long as the number
utilized can provide the
necessary wattage per inch of laser line L. Accordingly, those ordinarily
skilled in this art
having the benefit of this disclosure realize there are a variety of laser
combinations which could
provide this minimum wattage.
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[0067[ Further referring to the exemplary embodiment of Figure 13, the
combined use of the
three lasers 40 provides a higher light intensity, thereby producing a line of
light at a specific
wavelength which is more intense than the solar radiation at that same
wavelength. In this
exemplary embodiment, lasers 40 are each 808nm +1- 2nm wavelength lasers as
understood in
the art. This choice of laser wavelength corresponds to a dip in the solar
spectrum at
approximately 808nm caused by the sunlight penetrating the earth's atmosphere,
as illustrated in
the graph of Figure 16. Here, the solar spectrum is shown at sea level ranging
from roughly
400nm to above 2400nm, which includes UV, visible and infrared wavelengths. At
approximately 808nm, there is a sharp dip in sun's solar energy. Thus, the
808nm lasers utilized
in the present invention were specifically chosen because their wavelengths at
approximately
808nm are more intense than the solar radiation at the same wavelength,
thereby allowing their
radiated light to be detected in sunlight via cameras 50. Those ordinarily
skilled in the art having
the benefit of this disclosure realize other laser wavelengths may be utilized
to take advantage of
other dips in solar radiation, in accordance with the present invention.
[oo6s1 Referring to Figures 14 and 15, an exemplary alternative embodiment of
cameras 50 of
the present invention will now be described. As previously discussed, cameras
50 are mounted
to framework 32 and send image data of the inspected surface (in this example,
a railroad track)
to the processing device or computer 60 via wired or wireless transmission
lines. However, in
this exemplary embodiment, cameras 50 each include a housing 70 having a lens
72. Within
housing 70 is a charge coupled device 74, or CCD, which is an analog shift
register that enables
transmission of analog signals through successive stages controlled by a clock
signal. CCD 74
can be used as a form of memory or for delaying samples of analog signals, as
understood in the
art. In the alternative, however, a CMOS sensor as understood in the art may
be utilized to
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capture images as well. Those ordinarily skilled in the art having the benefit
of this disclosure
realize there are a variety of cameras which may be utilized with the present
invention.
]0069] As illustrated in Figure 15, CCD 74 is placed adjacent an optical
bandpass filter
76. In this exemplary embodiment, bandpass filter 76 was chosen to pass a band
of the laser 40's
wavelength -2nm and +lnm, while filtering at least OD4 for the remainder of
camera 50's
response range from 300nm to 1100nm, excluding the ramp-up and ramp-down areas
that exist
near the band pass region as understood by those ordinarily skilled in the art
having the benefit
of this disclosure. Therefore, by utilizing 808nm.lasers, bandpass filter 76
passes a wavelength
approximately 806-810nm, while filtering out the remaining solar radiation.
Since there is a dip
in the sun's radiation at this wavelength, the line generated by lasers 40 is
readily detectable in
the sunlight.
]0070] In order to reduce the blue shift associated with light passing through
a filter at an angle,
bandpass filter 76 is mounted between lens 72 and CCD 74. Typically, when
light passes
through a filter at extreme angles, in order to get the same wavelength of
light at many different
angles, you must have a filter with a wide passband. If a filter were placed
on the exterior of the
lens, light would come in at an extreme angle. However, by moving the filter
behind the lens,
the light is much more parallel and the blue shift effect is dramatically
decreased. This reduction
in the blue shift results in a much tighter filter bandpass, which is
necessary to filter out as much
solar radiation as possible. Accordingly, bandpass filter 76 is mounted behind
lens 72.
]0071] A spacer 78 is positioned on the other side of bandpass filter 76
opposite CCD 74.
Spacer 76 comprises an opening 80 which allows image data to be collected from
lens 72. In
this embodiment, bandpass filter 76 screens out as much inonlaser-generated
light as possible,
thereby enabling daytime inspection. Also, this embodiment results in a slight
increase in focal
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length due to the light passing through filter 76. This phenomenon is
compensated for by
mounting CCD 74 slightly further from lens 72 via the use of spacer 78 located
between lens 72
and camera housing 70. Spacer 78 changes the orientation of the lens 72
relative to CCD 74.
Spacer 78 may be, for example, a precision shim washer. In the alternative,
however, spacer 78
would not be necessary in embodiments utilizing a camera lens which has a
sufficiently wide
focusing range- Accordingly, those ordinarily skilled in the art having the
benefit of this
disclosure realize there are a variety of spacers which could be utilized with
the present
invention, and that the need for spacer 78 may be negated through lens choice.
10072] In yet another exemplary embodiment of the present invention, rail seat
abrasion may be
predicted with a high level of accuracy. This embodiment utilizes the image
data previously
described and the application of algorithms that adjust for vehicle tilt. As
inspection system 30
moves along the track, it may encounter curves or bends in the track which
result in a suspension
lean of the system 30 as it moves through the curve. This lean results in the
railroad track itself
leaning either to the left or right in the field of the cameras 50 view. The
resulting measurement
data is used to target which ties should be physically inspected for rail
abrasion. However, the
leaning, or tilt, must be taken into account when identifying ties to be
inspected for rail seat
abrasion, as will be described below.
[00731 The tilt phenomena is more clearly described in reference to the
profile image depicted in
Figure 17. Although this image would be three dimensional as previously
described, it is
illustrated here as a profile for simplicity. In this exemplary embodiment,
left and right rails 12
are illustrated laying atop concrete tie 10. Line L3 represents level ground.
Although not
shown, it is envisioned this section of the track is within a curve, and an
inspection system of the
present invention is moving along the track resulting in an angular tilt of
cross ties 10
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represented by line L4. As such, the track is tilting slightly to the left. In
order to determine
whether rail seat abrasion is present, height measurements of the each rail
must be taken in
accordance with the methods previously described. However, in this example,
the height of right
rail 12 would appear taller then left rail 12, resulting in skewed data.
measurements.
Accordingly, during significant empirical and mathematical research for the
present invention, a
standard tilt correction factor of 0.12 was determined. This tilt correction
factor is incorporated
into algorithms of the present invention in order to adjust for tilt caused by
variations in vehicle
suspension, rail height placement standards, and other factors unrelated. to
rail seat abrasion.
100741 In further reference to the exemplary embodiment of Figure 17 and the
exemplary flow
chart of Figure 18, a tilt correction algorithm for the present invention is
now described. Based
on the three-dimensional image data received from cameras 50 as previously
described, at step
100, a measurement is taken of the rail base height of each rail, left (HL '')
and right (H'`.), as
well as each tie, left (HLte) and right (H'uh`) The rail base and tie heights
are the heights of the
rails and ties relative to line L5, representing the top of the three-
dimensional image. Once the
dimensional images have been captured, the rail base heights and tie heights
are determined
based upon the vertical pixel count of HLf81', HRH'', HL"e and HRhe, which is
then normalized based
upon a 0-255 measurement index. In operation, the laser light reflected by the
track structure
that passes through the camera lens is projected onto the camera CCD, as
previously described.
The dimensions of each CCD, in an exemplary embodiment, are 256 pixels by 1536
pixels. In
this exemplary embodiment, there are two cameras placed roughly side by side.
Accordingly,
the total field of view for the two cameras combined has a field of view of
256 pixels by 3072
pixels - hence the 0-255 index. Those ordinarily skilled in the art having the
benefit of this
disclosure realized there are a variety of methods to determine the heights.
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io0751 Thereafter, at step 102, inspection system 30 records the uncorrected
HLa1, HRra11, HLEie
and HRC,e height measurements of rails 12 and tie 10 based upon the pixel
value of each. Then, at
step 104, the processor of inspection system 30 derives the tilt correction
factor (TC) based upon
the following equation:
TC = (HLrau - HRrail)(.12)
100761 Thereafeter, at step 106, the actual A (i.e., the distance/difference
between two points) is
determined for both the right and left rail bases based upon the following
equation:
A1eftRail ; (HLrail - HLae) - TC
QrightRai1 _ (HR-" - HR) + TC
The result is the actual A between the rail base height and tie elevation for
both the right and left
rails. Please note the foregoing equations take into account the lean, or
tilt, of the truck, whether
left or right.
100771 Then, at step 108, the rail seat abrasion value ("RSA") for the right
and left rail bases is
determined based upon the following formula:
RSALm" = (32154) - (Aleft ' / 50)
RSAR' ' = (32/54) - (A`'ghtRai1 / 50)
The "32/54" is the expected A between the rail base and tie elevation,
signifying no rail seat
abrasion. The "50" represents the rate of collection in height, 50 pixels per
inch. Those
ordinarily skilled in the art realize the 50 pixels inch rate of collection
could vary based upon the
geometry of the camera and laser setup.
(o07s1 Thereafter, at step 110, the RSA values are outputted in a form
suitable for further
analysis. At step 112, the next frame image is then analzed and the algorithm
begins again. The
RSA data provides accurate measurements of rail seat abrasion and allows for
effective, accurate
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identification of potential safety hazards and wear points requiring
monitoring or corrective
action to ensure track safety.
[00791 An exemplary system for determining rail seat abrasion of a rail road
track comprises at
least one light generator positioned adjacent the rail road track, the light
generator adapted to
project a beam of light across the rail road track; at least one camera
positioned adjacent the rail
road track for receiving at least a portion of the light reflected from the
rail road track and for
generating at least one image representative of a profile of at least a
portion of the rail road track,
and at least one processor adapted to perform the steps comprising: analyzing
the at least one
image; and determining whether rail seat abrasion is present along the rail
road track, wherein,
when determining whether rail seat abrasion is present, the at least one
processor compensates
for a tilt of the rail road track.
[00$01 In other exemplary embodiments, the processor compensates for the tilt
of the rail road
track by the steps comprising: determining a height of a left rail base, right
rail base, left crosstie
and right crosstie; determining a tilt correction factor; determining an
actual delta for the right.
and left rail bases; and determining a rail seat abrasion value for the right
and left rail bases. In
yet another exemplary embodiment, the step of determining the heights further
comprises the
steps of. determining vertical pixel counts for each of the heights of the
left rail base, right rail
base, left crosstie and right crosstie; and normalizing the vertical pixel
counts based upon a
measurement index.
roosii In other exemplary embodiments, the step of determining the tilt
correction factor is
accomplished based upon the left and right rail. base heights and a standard
tilt correction factor.
In yet another exemplary embodiment, the step of determining the actual delta
is accomplished
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based upon the tilt correction factor. Also, other embodiments provide for the
step of
determining the rail seat abrasion value to be accomplished based upon the
actual delta.
pop Exemplary methods of the present invention provide a method for
determining rail seat
abrasion of a rail road track, the method comprising the steps of determining
a height of a left
rail base, right rail base, left crosstie and right crosstie; recording the
heights of the left rail base,
right rail base, left crosstie and right crosstie; determining a tilt
correction factor; determining an
actual delta for the right and left rail bases; and determining a rail seat
abrasion value for the
right and left rail bases. Another exemplary method provides a method the step
of determining
the heights further comprises the steps of, determining vertical pixel counts
for each of the
heights of the left rail base, right rail base, left crosstie and right
crosstie; and normalizing the
vertical pixel counts based upon a measurement index.
100831 Further exemplary methods provide methods wherein the step of
determining the tilt
correction factor is accomplished based upon the left and right rail base
heights and a standard
tilt correction factor. In other examples, the step of determining the actual
delta is accomplished
based upon the tilt correction factor. In other examples, the step of
determining the rail seat
abrasion is accomplished based upon the actual delta for the right and left
rail bases.
[00941 In yet another exemplary method of the present invention, a method for
determining rail
seat abrasion of a rail road track is provided, the method comprising the
steps of. moving an
inspection system along the track; receiving image data corresponding to at
least a portion of the
track; determining a measurement of the rail seat abrasion for the. portion of
the track, wherein
the measurement are adjusted. for tilt encountered as the inspection system
moves along the
track; and determining whether rail seat abrasion exists based upon the
adjusted measurement.
In another exemplary method, the step of determining a measurement of the rail
seat abrasion
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further comprises the steps of: determining a height of a left rail base,
right rail base, left crosstie
and right crosstie; determining a tilt correction factor; determining an
actual delta for the right
and left rail bases; and determining a rail seat abrasion value.
[oo851 In other exemplary methods, the step of determining the heights further
comprises the
steps of: determining vertical pixel counts for each of the heights of the
left rail base, right rail
base, left crosstie and right crosstie; and normalizing the vertical pixel
counts based upon a
measurement index. In another exemplary method, the step of determining the
tilt correction
factor is accomplished based upon the left and right rail base heights and a
standard tilt
correction factor. In yet another method, the step of determining the actual
delta is accomplished
based upon the tilt correction factor. In another method, the step of
determining the rail seat
abrasion value is accomplished based upon the actual delta.
[00861 Although various embodiments have been shown and described, the present
invention is
not so limited and will be understood to include all such modifications and
variations as would
be apparent to one skilled in the art. Accordingly, the invention is not to be
restricted except in
light of the attached claims and their equivalents.
